Generally, a display panel has to undergo a test process before it is sent out for distribution, to ensure that a display panel's routing layout is arranged properly. One test solution for display panels is performed through a test circuit formed of transistors connected in series. Another test solution is known as laser cut. For this test solution, a test circuit is disposed on a display panel in the manufacturing process of display panels. After the test, the test circuit is cut off from the display panel through laser cutting.
However, disadvantages are found in both test solutions of display panels. For the laser cut test solution, because the test circuit is cut off in the end, the element size of the test circuit is not a concern. After the test circuit is cut off, however, any relevant electrical property test cannot be performed on the display panel. In other words, a vendor receiving a panel from a panel factory cannot perform relevant electrical property tests on the display panel, and thus makes it impossible to perform an incoming quality control (IQC). On the other hand, for the test solution performed through a plurality of transistors connected in series, volume miniaturization of a commonly formed thin film transistor has its limit. Further, the resolution of display panels has been enhanced continuously, making the size of a driving integrated circuit (IC) of a display panel being continuously reduced accordingly, resulting in a reduced line width or pitch of the driving IC of the display panel. Such a change has gone beyond the common capability of a current manufacturing process.